Air disinfection apparatus

ABSTRACT

An air purification and disinfection apparatus incorporates an air inlet filter ( 1 ) spanning the intake of the apparatus, an ultraviolet light source ( 2 ) for treating the air within a chamber ( 14 ) of the apparatus, and an equalising screen ( 3 ) spanning the outlet of the apparatus. The chamber ( 14 ) is lined with a reflective sheet ( 11 ) or coating such that the ultraviolet light is reflected around the chamber ( 14 ). The air inlet filter ( 1 ) removes larger airborne particles from the airflow prior to entering the chamber ( 14 ). The light source ( 2 ) may be located in the chamber ( 14 ) or in a housing ( 16 ) which communicates with the chamber ( 14 ). With the reflective surface of the chamber ( 14 ), the intensity of the light source ( 2 ) can be maintained when dirt begins to build up on the light source ( 2 ), thereby extending the length of time that passes between each cleaning of the light source ( 2 ).

This invention relates to apparatus for the disinfection andpurification of air either in forced air systems such as airconditioning and ventilation systems, or else as a portable, stand-aloneroom unit.

Ultraviolet light has been used for a number of years to remove bacteriafrom water in the process of disinfecting and purifying the water.Ultraviolet light has also been used for the same process in relation toair in forced air systems including air conditioning and ventilationsystems, although its use has been limited. The use of ultraviolet lightto remove bacteria and to disinfect water has been very effective, butits use in relation to the removal of bacteria from air and thedisinfection and purification of air has been less satisfactory. This isdue to the reduced efficiency of the ultraviolet lamp caused by dirtparticles attaching to the external surface of the lamp. Unfiltered dirtparticles in a forced air system attach themselves to the ultravioletlamp, greatly reducing its efficiency. This results in the need forregular maintenance and cleaning of the ultraviolet lamp.

An apparatus which can remove virtually all of the bacteria from the airin the forced air system will significantly reduce the respiratoryproblems and other health problems which are currently determined to becaused by air conditioning and ventilation systems.

It is the object of the present invention to provide a highly efficientair disinfection and purification apparatus which can be inserted in theducting of forced air systems including air conditioning and ventilationsystems. This apparatus will obtain much greater efficiency from theultraviolet lamp and will reduce the need for maintenance and cleaningof the ultraviolet lamp. The apparatus can alternatively be portable andcapable of simple positioning in a room, for example.

According to a first aspect of the present invention there is providedan air treatment apparatus comprising:

-   -   a chamber having an input and an output;    -   a filter means located adjacent said input; and    -   an ultraviolet light source projecting ultraviolet light into        said chamber;    -   wherein said chamber has at least one light-reflective surface.

Preferably, said filter means comprises a polarised air filter.

Preferably, said apparatus further comprises an equalising screenadjacent said output.

Preferably, said at least one light-reflective inner surface comprisesat least one light-reflective sheet removably inserted into saidchamber.

Preferably, said at least one light-reflective sheet is an aluminiumsheet. Alternatively, said at least one light-reflective inner surfacecomprises a surface coating applied to said at least onelight-reflective surface of said chamber.

In a preferred embodiment of the first aspect of the present invention,the chamber has four inner surfaces and has a substantially rectangularcross section.

In an alternative embodiment of the first aspect of the presentinvention, the chamber has one inner surface and has a substantiallycircular cross section.

Preferably, said at least one side wall of said passage contains aremovable portion. Preferably, said light source is fixedly attached tosaid removable portion. Preferably, said light source may be removedfrom said apparatus. Preferably, said light source comprises at leastone ultraviolet lamp. Preferably, said at least one ultraviolet lampemits ultraviolet light at a wavelength of between 230 nm and 290 nm.

Preferably, said light source lies in a substantially horizontal planeand is substantially perpendicular to the direction of airflow.Alternatively, said light source may lie in a substantially horizontalplane and is substantially parallel with the direction of airflow.

Preferably, said light source projects into the centre of said chamber.Preferably, said apparatus further comprises a deflector plate memberlocated within the chamber adjacent said air filter to deflect the airflow over said light source.

Alternatively, said light source is located outwith the chamber.Preferably, said housing has at least one side wall, the inner surfaceof which is a light-reflective surface.

Preferably, said light-reflective surface comprises a light-reflectivesheet removably attached to said inner surface. Preferably, saidlight-reflective sheet is an aluminium sheet. Alternatively, saidlight-reflective surface may be a surface coating applied to said innersurface.

In a preferred embodiment, the apparatus is located in a forced airsystem. In an alternative embodiment, the apparatus is portable.

According to a second aspect of the present invention, there is provideda method of treating air, comprising the steps of:

-   -   passing air through the inlet of a chamber having at least one        inner surface;    -   passing the air through a filter means adjacent said inlet;    -   subjecting the air to ultraviolet light within said chamber; and    -   exiting the air from said chamber through an outlet,    -   wherein the at least one side wall of the chamber has a        light-reflective surface.

Preferably, said method uses an apparatus in accordance with the firstaspect of the present invention.

Preferred embodiments of the invention will now be described by way ofexample only, with reference to the accompanying drawings, wherein:

FIG. 1 is a side elevation of a first embodiment of the air disinfectionand purification apparatus according to the present invention;

FIG. 2, is an end elevation of the air disinfection and purificationapparatus shown in

FIG. 1 with the air inlet filter removed for illustrative purposes;

FIG. 3 is a side elevation of a second embodiment of the airdisinfection and purification apparatus according to the presentinvention; and

FIG. 4 is an end elevation of the air disinfection and purificationapparatus shown in FIG. 3 with the equalising screen partially removedfor illustrative purposes.

FIGS. 1 and 2 show a first embodiment of the air disinfection andpurification apparatus incorporating an air inlet filter 1 spanning theintake of the apparatus. An ultraviolet lamp 2 is fixed centrally on aremovable side panel 12 of the apparatus and an equalising screen 3 isalso provided, spanning the outlet of the apparatus. The air enters theair disinfection and purification apparatus in the direction of thearrow 13, travels through a main chamber 14 housing the ultraviolet lamp2, and discharges into the ducting of the forced air system through theequalising screen 3.

The air inlet filter 1 spans and is attached to the front of the airdisinfection and purification apparatus. The air inlet filter 1 consistsof a wire mesh screen 4, to which is connected a 6,000 volt DC powersupply (not shown) which is fed by a 110 volt to 9 volt adapter (notshown). The wire mesh screen 4 is sandwiched between two glass fibremedia pads 5 that are polarised by the high voltage present in the wiremesh screen 4. The polarised glass fibre media pads 5 themselves aresandwiched between two grounded (i.e. earthed) outside metal screens 6.An inlet air deflector plate 15 may be positioned downstream of thefilter 1 to ensure that the air is deflected so as to pass over the lamp2, although it is to be understood that this is not an essentialcomponent of the apparatus.

The inlet filter 1 is a non-ionising, low-pressure drop filter whichprevents larger airborne particles from passing into the remainder ofthe apparatus downstream whilst not interfering significantly with theflow of air. The filter 1 may also include a non-ionising, low-pressuredrop carbon insert for the removal of gases and odours. The filter 1does not generate ozone, nor is the airflow ionised.

In this first embodiment, the ultraviolet lamp 2 is located centrally onthe removable panel 12 which is attached by screw attachments 7 whichare centrally placed on the top and bottom edges of the apparatus. Theattachments 7 also contain micro switches (not shown) so that when thescrews are removed, the switches open and the lamp 2 shuts down so thatit may be removed without harming maintenance personnel.

A flexible and reflective aluminium sheet 9 covering three of theinternal sides of the main chamber 14 of the apparatus is held in placeby four internal guides 10, through which the aluminium sheet 9 isinserted. The internal wall of the removable panel 12 is also coveredwith a reflective aluminium sheet 11, so that when the removable panel12 is attached to the main section of the apparatus, all of the internalwalls of the apparatus are covered with aluminium sheet.

An equalising screen 3 spans the outlet of the air disinfection andpurification apparatus. The equalising screen 3 comprises a lowresistance aluminium mesh screen designed to evenly distribute theairflow as it is discharged through the outlet into the forced airsystem.

With the incorporation of the reflective aluminium sheet 9,11, theefficiency of the lamp 2 is greatly improved. Over time, dirt will buildup on the lamp 2, reducing the effectiveness of the lamp 2 in spite ofthe inlet filter arrangement 1. However, the reflective sheet 9,11compensates for this build up by reflecting the light around the chamber14 and ensures that the ultraviolet light continues to disinfect the airduring use.

In the second embodiment of the present invention, as seen in FIGS. 3and 4, the majority of the elements described above in respect of thefirst embodiment are still present, and therefore will not be describedagain here. However, the difference between the first and secondembodiments is that the ultraviolet light source 2 in the secondembodiment is located in a housing 16 outwith the chamber 14. Thehousing 16 is fixed, by bolts, screws or the like to a side of the airduct. The housing 16 can either be manufactured from a reflectivematerial such as Aluminium, for example, or else reflective sheet suchas that used in the duct may be inserted into the housing 16. Thehousing 16 may also be fitted with a prevention screen (not shown) toprevent ozone from entering the chamber 14.

Therefore, in the second embodiment, the ultraviolet light emitted fromthe light source 2 may be directed into the chamber 14 by the reflectivematerial without the light source 2 having to be positioned in thechamber 14. Thus, there will be no build up of deposits on the lightsource 2 during operation, and the light source 2 will therefore notrequire cleaning.

The preferred ultraviolet light source in both of the aforementionedembodiments is one or more ultraviolet arc-tubes. The arc-tubes caneither be controlled from a integrated control panel (e.g. firstembodiment) or a remote control panel (e.g. second embodiment). Theaction of the ultraviolet light, preferably at wavelengths from 230 nmto 290 nm, causes microbial and viral disruption of the passing airflow.

As a result of the present invention, the air in forced air systems suchas air conditioning and ventilation systems can be disinfected andpurified by removing bacteria with minimal loss of airflow and a greatlyreduced need for maintenance and cleaning.

For the application of the present invention in forced air systems, anumber of advantages are gained over existing systems. One of the primeadvantages is that the reflective nature of the aluminium sheet 9, 11contained in the main chamber 14 of the apparatus increases theefficiency of the apparatus by ensuring that the strength of theultraviolet light is evenly distributed throughout the chamber 14. Withrespect to the first embodiment, the even distribution of theultraviolet light due to the high reflectivity of the aluminium sheet 9,11 compensates for the reduced output of ultraviolet light from theultraviolet lamp 2 as dirt particles attach to the external surface ofthe ultraviolet lamp 2 over time.

The air filter 1 greatly reduces the dirt particles entering the mainsection of the apparatus and thereby will also reduce the loss ofefficiency of the ultra violet lamp 2.

Another advantage of the present invention is that whilst the airdisinfection and purification apparatus can be installed during theconstruction of new forced air systems, including air conditioning andventilation systems, it can also be fitted into existing forced airsystems.

A further advantage is that the need to clean and replace theultraviolet lamp 2 is either greatly reduced or obviated altogether. Itis expected that the first embodiment of the present invention willefficiently remove bacteria from the airflow travelling through theforced air system for six months without the need for cleaning. Atpresent, existing ultraviolet systems require the lamps to be cleaned atleast once every two months or so. It is anticipated that the secondembodiment of the present invention will not require any cleaning atall.

The filters used in the air inlet filter are comprised of low costdispensable media and can be removed and replaced at three monthlyintervals. As a result the cleaning and maintenance of the airdisinfection and purification apparatus will only require to be carriedout quarterly, thereby reducing the cleaning and maintenance costssubstantially.

It is anticipated that the air disinfection apparatus has a number ofother applications other than its use in air conditioning andventilation systems in buildings. Similar systems may also beincorporated in cars, buses, sea-faring vessels and aeroplanes and anyother manufacturing application which would benefit from thedisinfection and purification of air circulating in a forced air system.

Modifications and improvements can be incorporated without departingfrom the scope of the invention.

For example, although the aforementioned embodiments describe theinvention when located in a forced air system, it is also possible toproduce the apparatus as a portable unit. In this way, the unit can beplaced anywhere in a room and operate in the same manner as describedabove.

Furthermore, although it is anticipated that the reflective sheetcovering the internal walls of the chamber and housing is made ofaluminium sheet, the scope of the invention is not limited to the use ofaluminium sheet. Any other material whether metallic or non-metallicthat is suitably pliable and reflective may be used in place ofaluminium sheet. Furthermore, the reflective sheet may be replacedaltogether with a suitable reflective coating applied to the relevantsurfaces.

Another modification could be to reposition the light source of thefirst embodiment such that it is substantially parallel to the airflowrather than transversely positioned. It has been shown that having thelight source oriented in such a way may further improve the efficiencyof the apparatus.

1. An air treatment apparatus comprising: a treatment chamber having aninput and an output and at least one light-reflective inner surface; afilter means located adjacent the input; and an ultraviolet light sourcelocated downstream of the filter and projecting ultraviolet light intothe treatment chamber, wherein the light source is located outwith thetreatment chamber.
 2. The apparatus of claim 1, wherein the light sourceis located within a housing outwith the treatment chamber, the housinghaving at least one side wall and an aperture adapted to permitprojection of the ultraviolet light into the treatment chamber, theinner surface of the at least one side wall being a light-reflectivesurface.
 3. The apparatus of claim 2, wherein the aperture is providedwith an ozone prevention screen.
 4. The apparatus of claim 2, whereinthe light-reflective surface of the housing comprises a light-reflectivesheet removably attached to the inner surface.
 5. The apparatus of claim4, wherein the light-reflective sheet is an Aluminium sheet.
 6. Theapparatus of claim 2, wherein the light-reflective surface of thehousing is a surface coating applied to the inner surface.
 7. Theapparatus of claim 1, wherein the filter means comprises a polarised airfilter.
 8. The apparatus of claim 1, wherein the apparatus furthercomprises an equalising screen adjacent said output.
 9. The apparatus ofclaim 1, wherein the at least one light-reflective inner surface of thetreatment chamber comprises at least one light-reflective sheetremovably inserted into the treatment chamber.
 10. The apparatus ofclaim 9, wherein the at least one light-reflective sheet is an Aluminiumsheet.
 11. The apparatus of claim 1, wherein the at least onelight-reflective inner surface of the treatment chamber comprises asurface coating applied to the at least one inner surface of thetreatment chamber.
 12. The apparatus of claim 1, wherein the treatmentchamber has four inner surfaces and a substantially rectangular crosssection.
 13. The apparatus of claim 1, wherein the treatment chamber hasone inner surface and has a substantially circular cross section. 14.The apparatus of claim 1, wherein the light source comprises at leastone ultraviolet lamp.
 15. The apparatus of claim 14, wherein the atleast one ultraviolet lamp emits ultraviolet light at a wavelength ofbetween 230 nm and 290 nm.
 16. The apparatus of claim 1, wherein thelight source may be removed from the apparatus.
 17. The apparatus ofclaim 1, wherein the apparatus is located in a forced air system. 18.The apparatus of claim 1, wherein the apparatus is portable.
 19. Amethod of treating air comprising the steps of: passing air through theinlet of a treatment chamber having at least one light-reflective innersurface; passing the air through a filter means adjacent said inlet;subjecting the air to ultraviolet light within said treatment chamber;and exiting the air from said treatment chamber through an outlet,wherein the light source is located outwith the treatment chamber.
 20. Amethod of treating air comprising the steps of: passing air through atreatment chamber having an input and an output and at least onelight-reflective inner surface; passing the air through a filter meanslocated adjacent the input; providing an ultraviolet light sourceoutwith the treatment chamber and located downstream of the filter;directing ultraviolet light from the ultraviolet light source into thetreatment chamber; subjecting the air to ultraviolet light within thetreatment chamber; and exiting the air from the treatment chamberthrough the output.